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From:   Vishal Annapurve <vannapurve@google.com>
Date:   Mon, 19 Jun 2023 12:11:50 -0700
Message-ID: <CAGtprH8O6dsjjNrMzLPmRio0ZDLe6M3U06HD0oNX3NN9FeWQfg@mail.gmail.com>
Subject: Re: [RFC PATCH 0/6] KVM: guest memory: Misc enhacnement
To:     isaku.yamahata@intel.com
Cc:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
        isaku.yamahata@gmail.com, Paolo Bonzini <pbonzini@redhat.com>,
        erdemaktas@google.com, Sean Christopherson <seanjc@google.com>,
        Sagi Shahar <sagis@google.com>,
        David Matlack <dmatlack@google.com>,
        Kai Huang <kai.huang@intel.com>,
        Zhi Wang <zhi.wang.linux@gmail.com>, chen.bo@intel.com,
        linux-coco@lists.linux.dev,
        Chao Peng <chao.p.peng@linux.intel.com>,
        Ackerley Tng <ackerleytng@google.com>,
        Michael Roth <michael.roth@amd.com>
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On Thu, Jun 15, 2023 at 1:12=E2=80=AFPM <isaku.yamahata@intel.com> wrote:
> ...
>
> * VM type: Now we have KVM_X86_PROTECTED_VM. How do we proceed?
>   - Keep KVM_X86_PROTECTED_VM for its use. Introduce KVM_X86_TDX_VM
>   - Use KVM_X86_PROTECTED_VM for TDX. (If necessary, introduce another ty=
pe in
>     the future)
>   - any other way?

There are selftests posted[1] in context of this work, which rely on
KVM_X86_PROTECTED_VM being just the software-only psuedo-confidential
VMs. In future there might be more work to expand this usecase to
full-scale VMs. So it would be better to treat protected VMs as a
separate type which can be used on any platform without the need of
enabling TDX/SEV functionality.

TDX VM type can possibly serve as a specialized type of protected VM
with additional arch specific capabilities enabled.

[1] - https://github.com/sean-jc/linux/commits/x86/kvm_gmem_solo